Tachometer arrangement for outboard motors



Ap 1951 E. c. KIEKHAEFER 2,549,480

TACHOMETER ARRANGEMENT FQR OUTBOARD MOTORS '1Fifl.-eid;-S.ept. 5, 1947 a 4 Sheets-Sheet l I INVENTOR. ELME-R C. MEI/(HA5: r212 April 17, 1951 5.. c. KIEKHAEFER TACHOMETER ARRANGEMENT FOR OUTBOZQRD MOTORS Filed Sept. 5, 1947 4 Sheets-Sheet 3 I N VEN TOR.

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p 1951 E. c. KIEKHAEFER TACHOMETER ARRANGEMENT FOR OUTBOARD MOTORS Eiledi SE91. 5,, 1947 4 SheeisrSheetK; 4'

Wi y/ 6 TTOR/VE Y tachometer and engine shaft.

Patented Apr. 17, 1951 UNITED STAT TACHOMETER ARRANGEMENT FOR OUTBOARD MOTORS Elmer C. Kiekhaefer, Cedarburg, Wis. Application September 5, 1947; Serial No. 772,345

3 Claims.

This invention relates to outboard motors and has particular reference to.a speed recording device for an outboard motor.

The primary object of the invention is to provide means for rendering the drive shaft of a tachometer accessible to the engine shaft of the outboard motor.

A specific object is to provide an outboard motor having a starter shaft hollowed to accommodate a driving connection between the Another object of my invention is a startershafthollowed to accommodate the cable and casing of a tachometer anchored remotely from the outboard motor.

Another object is to provide a starter shaft, hollowed to serve as a housing for the drive shaft of a tachometer mounted directly to the outboard motor.

Other objects and advantages will become apparent upon reading the following specification and upon examination of the drawings in which:

Fig. 1 is a side elevation of an outboard motor employing the invention in one form;

Fig. 2 is a fragmentary sectional side view of the outboard motor employing one form of the invention;

Fig. 3 is a fragmentary sectional front view of the outboard motor employing a modified form of the invention;

Fig. 4 is a detail plan view of the upper end of the engine shaft; and

Fig. 5 is a fragmentary sectional front view of the outboard motor employing another modifled form of the invention.

The outboard motor in general comprises a' power head I, a drive shaft housing '2, a'propeller shaft housing 3, a propeller 4, a boat clamping bracket 5 and a tiller 6.

The power head I includes an internal combustion engine housed in a pair of casings .8 and 9 secured together, the parting line of said casings beingembraced by a protector rim ID.

The engine 1 may have one or more pistons II and cylinders l2 with a single crankshaft l3 and may have a cylinder block l4 and a crankto provide Al to facilitate insertion of drive tip 38.

. 2 to cover 23. ,Itwill be noted that the starter shaft 2| is in concentric registry with engine shaft l3. 7

-In outboard motor construction it is desirable to know the R. P. M. at which the engine shaft is revolving, particularly when selecting the propeller with the proper diameter and pitch for maximum performance. For example, an outboard motor of the type employed herein, operates at near maximum efliciency with near maximum horsepower output when the crank- .shaft [3 is revolving at 4400 R. P. M. Consequently, I have provided an expedient and coonomical means for permanently associating a tachometer with an outboard motor so that an R. P. M. reading of the engine shaft is constantly available.

In Fig. 2, I have shown one form of my invention in which the cover 23 is provided with a bore 21 which registers with a bore 28 in starter shaft 2|. A conventional tachometer 29 may be secured to some part of the boat 38 remotely from the outboard motor so that the dial 3| faces the'operator of the boat. The tachometer 29 is provided with a flexible housing 32 which serves as a bearing for the flexible drive shaft 33. An externally threaded sleeve 34 may be welded or brazed to the end of the housing 32 and is threaded into the internally threaded lower portion of bore 28 in starter shaft 2|. The housing 32 bottoms against an annular shoulder 35. The lower portion of the starter shaft 2| may have an enlarged bore 36 to accommodate shaft seal 31 for retaining lubricant in housing 32'. The flexible drive shaft 33 has a driving tip 38 which has an internal bore at one end to receive the end of flexible shaft 33 and has a driving ear 39 near its other end. The ear 39 may be formed in the drive tip 38 by a swagingprocess. The endof the engine shaft l3 has a drilled hole 49 which may be countersunk at A saw slot 42 is cut in the engine shaft and opens into drilled hole 40 to receive the driving ear 39.

, Thus it can be seen that rotation of engine shaft is directly transmitted to the flexible drive shaft 33, through the medium of the driving ear 39 and the R. P. M. of the engine shaft is recorded by the tachometer 29.

The flexible shaft 33 may be assembled by inserting the tachometer end of the shaft into bore 28 through the flexible housing 32 prior to the time that the cover 23 and its attached starter assembly is inserted into place in casing 8. Then the cover 23 and its associated parts are broughtinto position over casing 8 and manipulated until the driving ear 39 slips into the saw slot 42 in the engine shaft. Then the cover 23 is secured to casing 8 by suitable screws. Thus it is apparent that the starter shaft 21 serves the dual function of supporting the starter pulley l9 and its associated parts externally thereof, while accommodating the tachometer drive shaft 33 and housing 32 internally thereof.

In the form of my invention as disclosed in Fig. 3 the starter shaft 21a may have an annular fiange 24a which is nested in a circular recess 44 in cover 23a and secured to the cover with screws 25a. The starter shaft has an internalbore 28a of sufficient diameter to provide a clearance between the cylindrical wall of the bore and the driving tip 45. The driving tip may have a squared nose portion 46 which is received in a correspondingly shaped hole 4'! in the upper end of the engine shaft l3a thereby establishing a driving connection between engine shaft [3a and driving tip 45. The square shaped hole 4-7 may be obtained by running a broaching tool into a drilled hole 48. The drilled hole 43 is countersunk at 49 to facilitate entry of driving-tip 45 into hole 41.-

Theupper end ofstarter shaft 2 la has an externally threaded nipple 50 protruding beyond the face of cover 23a, the interior of said nipple being machined to provide a semi-spherical receptacle for the sph rically shaped upper end 5| of driving tip =25. An externally threaded nut 52 having a semi-spherical interior mating with the semi-spherical interior of the nipple 5:: to form a socket for the spherical upper end all of drive tip 35. The flexible housing 32a has a female end-fitting litthreaded onto the nut 52 and nipple 56. The flexible shaft 33a has a driving tip with an integral driving ear 55' received in a saw slot 55 which opens into the drilled hole 51. Thus-the engine shaft 5 3a drives the connector 45 which in turn drives the flexible shaft 33a thereby affording a reading at the tachometer 29a of the R; P. M. of the engine shaft. It will be noted that the bore 28a in the starter shaft 2 fa serves as a housing for the connector shaft 55 and the clearance between the shaft and the wall of bore 28a in combination with the ball and socket joint at the upper end of shaft connector 45 per- Inits some misalignment between the connector shaft 35 and the bored? of the engine shaft 13a which may be present when cover 23a is assembled into casing 8a.

In the form of the invention as disclosed in Fig. 5, I have mounted the tachometer 29b directlyont'o the cover 23b by means of a supporting bracket 59 and bolts 66. Rubber pads 6i interposed between the bracket legs and the cover 23?) serve to damp out vibration so that a more accurate reading may be obtained from the tachometer 29b. The engine shaft [3.2) has a drilled hole 4% with a saw slot 4% for receiving thedriving ear 3% of connector shaft 33 thereby establishing a driving connection between engine shaft i322 and connector shaft 63. The starter shaft has a bore 281) mating with a bore 271) in cover 28?) and the starter shaft Zlb and cover serve asa housing and bearing for the connector shaft 53. A pair of seals S t and 85 retain lubricant. within the bores 22b and 28b. The connector shaft 63 may be threaded into the driven shaft 65 of the tachometer 28b. The tachometer has an externally threaded stud 6'! which projects through an opening in bracket 59 and a pair of nuts 58 and G9 secure the tachometer to the bracket 59. The connector shaft 63 is ass bled. by bein n er ed, through the starter shaft 2Ib from its underneath side. Then the cover 23b and its associated parts are assembled into casing 822 and secured thereto. The driven shaft 66 of the tachometer is then threaded onto the upper end of the connector shaft 63 and the tachometer is secured to bracket 59 with nuts 68 and GS.

Itis apparent that I have provided a comparatively simple yet economical and expedient way of providing an outboard motor with a tachometer driven by the engine shaft so as to obtain the R. P. M; reading of the engine shaft for various purposes.

Having thus described my invention what I claim is: V a

1. In an outboard motor, a power unit including a crankshaft, a starter device for said power unit including a pulley rotatably engageable with said crankshaft, a removable starter cover plate having'a hub rotatably carrying said pulley in axial alignment-With said crankshaft and axially spaced therefrom, said plate having an opening extending-through said hub in axial alignment with said crankshaft, 'a speed indicating instrument having av shaft extending through said opening and said starter cover hub and drivingly engageable with said crankshaft, and a bearing secured to and carried by said cover plate journally-supporting said instrument shaft in said opening.

2; in an outboard motor, a power unit'having a crankshaft; astarter device'for said power unit including a pulley'rotatably engageable with said crankshaft, a startercover plate having a hollow hubrotatably. carrying said pulley in axial alignment with said crankshaft and spaced therefrom, a speed indicating instrument including a flexible shaft extending through said starter cover plate huband drivingly connected to said crankshaft; and a flexible housing for said flexible, shaft secured and carried within said hollow hub and journally. supporting said flexible shaft therein.

3. In an outboard motor, a power unit having a crankshaft, a starter device for said power unit including. a pulley rotatably engageable with said crankshaft, astarter cover plate having a hollow hub rotatably carrying said pulley in axial alignment with said crankshaft and spaced therefrom, a speed indicating instrument including a flexilcle shaft extending through said hub and drivingly connectable with said crankshaft, and a flexible housing for. saidfiexible shaft secured to and carriedby said hub' and journally supporting therein.

saidflexible shaft ELMIER C. KIEKHAEFER.

nnrnnnrqoss CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

